Implementing std::filesystem::remove_all() for AndroidEPUB reader for AndroidMonitor filesystem for...
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Implementing std::filesystem::remove_all() for Android
EPUB reader for AndroidMonitor filesystem for continuous integration and buildValidating FileSystem StructureImplementing FusedLocationProvider for more than one Activity in Androidany_function using the upcoming std::any`std::move_as_tuple` and `std::when_all`Generalizing std::minmax_elementC++ std::array wrapperDisassembler for intel 8080Disassembler for intel 8080 v2
.everyoneloves__top-leaderboard:empty,.everyoneloves__mid-leaderboard:empty,.everyoneloves__bot-mid-leaderboard:empty{ margin-bottom:0;
}
$begingroup$
I needed to use some c++ code on both standard Linux and the Android variant, and the code will use filesystem library but it isn't yet in the ndk.
So I'm making a one to use on Android
It will be also usable on Linux because working with files and dirs go through the linux api which is the same on android
So, this is my implementation of the remove_all() function.
It reports errors in int variable and may be wrapped later with a function that will translate expected errno to proper c++ err_code.
It can't delete a dir that contains subdir with files exceeding the file descriptors limit for current process.
Also it can take the whole stack if called recursively too many times.
My filesystem implementation uses a thread local variable (int filesystem_errno) to store errors if needed.
size_t remove_all(const filesystem::path& p, int& err = filesystem_errno)
{
int dir_fd = open(p.c_str(),O_RDONLY|O_DIRECTORY);
if (dir_fd < 0)
{
err = errno;
return 0;
}
if (p.native().length() > PATH_MAX)
{
close(dir_fd);
err = ENAMETOOLONG;
return 0;
}
const int BUFF_SIZE = 1024;
char buffer[BUFF_SIZE];
char subdir[PATH_MAX];
int base_dir_len = strlen(p.c_str());
memcpy(subdir,p.c_str(),base_dir_len);
if (subdir[base_dir_len - 1] != '/')
{
subdir[base_dir_len] = '/';
++base_dir_len;
}
char *subdir_ptr = subdir;
subdir_ptr += base_dir_len;
struct linux_dirent
{
unsigned long inod;
off64_t off;
unsigned short len;
unsigned char type;
char name[];
};
struct linux_dirent32
{
unsigned long inod;
off_t off;
unsigned short len;
char name[];
};
linux_dirent *ldir_ptr;
linux_dirent32 *ldir_ptr32;
size_t fd_count = 0;
while(true)
{
int nread = syscall(SYS_getdents64,dir_fd,buffer,BUFF_SIZE);
if (!nread)
break;
if (nread == -1)
{
err = errno;
close(dir_fd);
return fd_count;
}
for (int pos = 0; pos < nread; pos += ldir_ptr->len)
{
ldir_ptr = (linux_dirent*)(buffer + pos);
// skip . and ..
if (ldir_ptr->name[0] == '.')
{
if (ldir_ptr->name[1] == 0)
continue;
else if (ldir_ptr->name[1] == '.')
if (ldir_ptr->name[2] == 0)
continue;
}
int subdir_len = strlen(ldir_ptr->name);
if ((subdir_len + base_dir_len) > PATH_MAX)
{
close(dir_fd);
err = ENAMETOOLONG;
return fd_count;
} memcpy(subdir_ptr,ldir_ptr->name,subdir_len);
subdir_ptr[subdir_len] = 0;
if (ldir_ptr->type == DT_DIR)
{
size_t deleted_dirs = 0;
if (!rmdir(subdir)) // empty dir
++deleted_dirs;
else if (!(deleted_dirs = filesystem::remove_all(subdir,err)))
{
close(dir_fd);
return fd_count;
}
fd_count += deleted_dirs;
}
else if (ldir_ptr->type != DT_UNKNOWN)
{
if(unlink(subdir))
{
err = errno;
close(dir_fd);
return fd_count;
}
++fd_count;
}
else
{
struct stat st;
if (stat(subdir,&st))
{
err = errno;
close(dir_fd);
return fd_count;
}
if (filesystem::is_directory(st))
{
size_t deleted_dirs = 0;
if (!rmdir(subdir))
++deleted_dirs;
else if (!(deleted_dirs = filesystem::remove_all(subdir,err)))
{
close(dir_fd);
return fd_count;
}
fd_count += deleted_dirs;
}
else
{
if (unlink(subdir))
{
err = errno;
close(dir_fd);
return fd_count;
}
++fd_count;
}
}
}
}
close(dir_fd);
if (rmdir(p.c_str()))
{
err = errno;
return fd_count;
}
err = 0;
++fd_count;
return fd_count;
}
c++ android file-system linux c++17
edited 2 days ago
Deduplicator
11.9k1950
asked 2 days ago
prog511prog511
61
$endgroup$
add a comment |
$begingroup$
I needed to use some c++ code on both standard Linux and the Android variant, and the code will use filesystem library but it isn't yet in the ndk.
So I'm making a one to use on Android
It will be also usable on Linux because working with files and dirs go through the linux api which is the same on android
So, this is my implementation of the remove_all() function.
It reports errors in int variable and may be wrapped later with a function that will translate expected errno to proper c++ err_code.
It can't delete a dir that contains subdir with files exceeding the file descriptors limit for current process.
Also it can take the whole stack if called recursively too many times.
My filesystem implementation uses a thread local variable (int filesystem_errno) to store errors if needed.
size_t remove_all(const filesystem::path& p, int& err = filesystem_errno)
{
int dir_fd = open(p.c_str(),O_RDONLY|O_DIRECTORY);
if (dir_fd < 0)
{
err = errno;
return 0;
}
if (p.native().length() > PATH_MAX)
{
close(dir_fd);
err = ENAMETOOLONG;
return 0;
}
const int BUFF_SIZE = 1024;
char buffer[BUFF_SIZE];
char subdir[PATH_MAX];
int base_dir_len = strlen(p.c_str());
memcpy(subdir,p.c_str(),base_dir_len);
if (subdir[base_dir_len - 1] != '/')
{
subdir[base_dir_len] = '/';
++base_dir_len;
}
char *subdir_ptr = subdir;
subdir_ptr += base_dir_len;
struct linux_dirent
{
unsigned long inod;
off64_t off;
unsigned short len;
unsigned char type;
char name[];
};
struct linux_dirent32
{
unsigned long inod;
off_t off;
unsigned short len;
char name[];
};
linux_dirent *ldir_ptr;
linux_dirent32 *ldir_ptr32;
size_t fd_count = 0;
while(true)
{
int nread = syscall(SYS_getdents64,dir_fd,buffer,BUFF_SIZE);
if (!nread)
break;
if (nread == -1)
{
err = errno;
close(dir_fd);
return fd_count;
}
for (int pos = 0; pos < nread; pos += ldir_ptr->len)
{
ldir_ptr = (linux_dirent*)(buffer + pos);
// skip . and ..
if (ldir_ptr->name[0] == '.')
{
if (ldir_ptr->name[1] == 0)
continue;
else if (ldir_ptr->name[1] == '.')
if (ldir_ptr->name[2] == 0)
continue;
}
int subdir_len = strlen(ldir_ptr->name);
if ((subdir_len + base_dir_len) > PATH_MAX)
{
close(dir_fd);
err = ENAMETOOLONG;
return fd_count;
} memcpy(subdir_ptr,ldir_ptr->name,subdir_len);
subdir_ptr[subdir_len] = 0;
if (ldir_ptr->type == DT_DIR)
{
size_t deleted_dirs = 0;
if (!rmdir(subdir)) // empty dir
++deleted_dirs;
else if (!(deleted_dirs = filesystem::remove_all(subdir,err)))
{
close(dir_fd);
return fd_count;
}
fd_count += deleted_dirs;
}
else if (ldir_ptr->type != DT_UNKNOWN)
{
if(unlink(subdir))
{
err = errno;
close(dir_fd);
return fd_count;
}
++fd_count;
}
else
{
struct stat st;
if (stat(subdir,&st))
{
err = errno;
close(dir_fd);
return fd_count;
}
if (filesystem::is_directory(st))
{
size_t deleted_dirs = 0;
if (!rmdir(subdir))
++deleted_dirs;
else if (!(deleted_dirs = filesystem::remove_all(subdir,err)))
{
close(dir_fd);
return fd_count;
}
fd_count += deleted_dirs;
}
else
{
if (unlink(subdir))
{
err = errno;
close(dir_fd);
return fd_count;
}
++fd_count;
}
}
}
}
close(dir_fd);
if (rmdir(p.c_str()))
{
err = errno;
return fd_count;
}
err = 0;
++fd_count;
return fd_count;
}
c++ android file-system linux c++17
edited 2 days ago
Deduplicator
11.9k1950
asked 2 days ago
prog511prog511
61
$endgroup$
$begingroup$
Is there a reason to not useopendir/readdirAPI?
$endgroup$
– vnp
yesterday
$begingroup$
This is much faster for dirs with too many files .
$endgroup$
– prog511
yesterday
add a comment |
$begingroup$
I needed to use some c++ code on both standard Linux and the Android variant, and the code will use filesystem library but it isn't yet in the ndk.
So I'm making a one to use on Android
It will be also usable on Linux because working with files and dirs go through the linux api which is the same on android
So, this is my implementation of the remove_all() function.
It reports errors in int variable and may be wrapped later with a function that will translate expected errno to proper c++ err_code.
It can't delete a dir that contains subdir with files exceeding the file descriptors limit for current process.
Also it can take the whole stack if called recursively too many times.
My filesystem implementation uses a thread local variable (int filesystem_errno) to store errors if needed.
size_t remove_all(const filesystem::path& p, int& err = filesystem_errno)
{
int dir_fd = open(p.c_str(),O_RDONLY|O_DIRECTORY);
if (dir_fd < 0)
{
err = errno;
return 0;
}
if (p.native().length() > PATH_MAX)
{
close(dir_fd);
err = ENAMETOOLONG;
return 0;
}
const int BUFF_SIZE = 1024;
char buffer[BUFF_SIZE];
char subdir[PATH_MAX];
int base_dir_len = strlen(p.c_str());
memcpy(subdir,p.c_str(),base_dir_len);
if (subdir[base_dir_len - 1] != '/')
{
subdir[base_dir_len] = '/';
++base_dir_len;
}
char *subdir_ptr = subdir;
subdir_ptr += base_dir_len;
struct linux_dirent
{
unsigned long inod;
off64_t off;
unsigned short len;
unsigned char type;
char name[];
};
struct linux_dirent32
{
unsigned long inod;
off_t off;
unsigned short len;
char name[];
};
linux_dirent *ldir_ptr;
linux_dirent32 *ldir_ptr32;
size_t fd_count = 0;
while(true)
{
int nread = syscall(SYS_getdents64,dir_fd,buffer,BUFF_SIZE);
if (!nread)
break;
if (nread == -1)
{
err = errno;
close(dir_fd);
return fd_count;
}
for (int pos = 0; pos < nread; pos += ldir_ptr->len)
{
ldir_ptr = (linux_dirent*)(buffer + pos);
// skip . and ..
if (ldir_ptr->name[0] == '.')
{
if (ldir_ptr->name[1] == 0)
continue;
else if (ldir_ptr->name[1] == '.')
if (ldir_ptr->name[2] == 0)
continue;
}
int subdir_len = strlen(ldir_ptr->name);
if ((subdir_len + base_dir_len) > PATH_MAX)
{
close(dir_fd);
err = ENAMETOOLONG;
return fd_count;
} memcpy(subdir_ptr,ldir_ptr->name,subdir_len);
subdir_ptr[subdir_len] = 0;
if (ldir_ptr->type == DT_DIR)
{
size_t deleted_dirs = 0;
if (!rmdir(subdir)) // empty dir
++deleted_dirs;
else if (!(deleted_dirs = filesystem::remove_all(subdir,err)))
{
close(dir_fd);
return fd_count;
}
fd_count += deleted_dirs;
}
else if (ldir_ptr->type != DT_UNKNOWN)
{
if(unlink(subdir))
{
err = errno;
close(dir_fd);
return fd_count;
}
++fd_count;
}
else
{
struct stat st;
if (stat(subdir,&st))
{
err = errno;
close(dir_fd);
return fd_count;
}
if (filesystem::is_directory(st))
{
size_t deleted_dirs = 0;
if (!rmdir(subdir))
++deleted_dirs;
else if (!(deleted_dirs = filesystem::remove_all(subdir,err)))
{
close(dir_fd);
return fd_count;
}
fd_count += deleted_dirs;
}
else
{
if (unlink(subdir))
{
err = errno;
close(dir_fd);
return fd_count;
}
++fd_count;
}
}
}
}
close(dir_fd);
if (rmdir(p.c_str()))
{
err = errno;
return fd_count;
}
err = 0;
++fd_count;
return fd_count;
}
c++ android file-system linux c++17
edited 2 days ago
Deduplicator
11.9k1950
asked 2 days ago
prog511prog511
61
$endgroup$
I needed to use some c++ code on both standard Linux and the Android variant, and the code will use filesystem library but it isn't yet in the ndk.
So I'm making a one to use on Android
It will be also usable on Linux because working with files and dirs go through the linux api which is the same on android
So, this is my implementation of the remove_all() function.
It reports errors in int variable and may be wrapped later with a function that will translate expected errno to proper c++ err_code.
It can't delete a dir that contains subdir with files exceeding the file descriptors limit for current process.
Also it can take the whole stack if called recursively too many times.
My filesystem implementation uses a thread local variable (int filesystem_errno) to store errors if needed.
size_t remove_all(const filesystem::path& p, int& err = filesystem_errno)
{
int dir_fd = open(p.c_str(),O_RDONLY|O_DIRECTORY);
if (dir_fd < 0)
{
err = errno;
return 0;
}
if (p.native().length() > PATH_MAX)
{
close(dir_fd);
err = ENAMETOOLONG;
return 0;
}
const int BUFF_SIZE = 1024;
char buffer[BUFF_SIZE];
char subdir[PATH_MAX];
int base_dir_len = strlen(p.c_str());
memcpy(subdir,p.c_str(),base_dir_len);
if (subdir[base_dir_len - 1] != '/')
{
subdir[base_dir_len] = '/';
++base_dir_len;
}
char *subdir_ptr = subdir;
subdir_ptr += base_dir_len;
struct linux_dirent
{
unsigned long inod;
off64_t off;
unsigned short len;
unsigned char type;
char name[];
};
struct linux_dirent32
{
unsigned long inod;
off_t off;
unsigned short len;
char name[];
};
linux_dirent *ldir_ptr;
linux_dirent32 *ldir_ptr32;
size_t fd_count = 0;
while(true)
{
int nread = syscall(SYS_getdents64,dir_fd,buffer,BUFF_SIZE);
if (!nread)
break;
if (nread == -1)
{
err = errno;
close(dir_fd);
return fd_count;
}
for (int pos = 0; pos < nread; pos += ldir_ptr->len)
{
ldir_ptr = (linux_dirent*)(buffer + pos);
// skip . and ..
if (ldir_ptr->name[0] == '.')
{
if (ldir_ptr->name[1] == 0)
continue;
else if (ldir_ptr->name[1] == '.')
if (ldir_ptr->name[2] == 0)
continue;
}
int subdir_len = strlen(ldir_ptr->name);
if ((subdir_len + base_dir_len) > PATH_MAX)
{
close(dir_fd);
err = ENAMETOOLONG;
return fd_count;
} memcpy(subdir_ptr,ldir_ptr->name,subdir_len);
subdir_ptr[subdir_len] = 0;
if (ldir_ptr->type == DT_DIR)
{
size_t deleted_dirs = 0;
if (!rmdir(subdir)) // empty dir
++deleted_dirs;
else if (!(deleted_dirs = filesystem::remove_all(subdir,err)))
{
close(dir_fd);
return fd_count;
}
fd_count += deleted_dirs;
}
else if (ldir_ptr->type != DT_UNKNOWN)
{
if(unlink(subdir))
{
err = errno;
close(dir_fd);
return fd_count;
}
++fd_count;
}
else
{
struct stat st;
if (stat(subdir,&st))
{
err = errno;
close(dir_fd);
return fd_count;
}
if (filesystem::is_directory(st))
{
size_t deleted_dirs = 0;
if (!rmdir(subdir))
++deleted_dirs;
else if (!(deleted_dirs = filesystem::remove_all(subdir,err)))
{
close(dir_fd);
return fd_count;
}
fd_count += deleted_dirs;
}
else
{
if (unlink(subdir))
{
err = errno;
close(dir_fd);
return fd_count;
}
++fd_count;
}
}
}
}
close(dir_fd);
if (rmdir(p.c_str()))
{
err = errno;
return fd_count;
}
err = 0;
++fd_count;
return fd_count;
}
c++ android file-system linux c++17
c++ android file-system linux c++17
edited 2 days ago
Deduplicator
11.9k1950
asked 2 days ago
prog511prog511
61
edited 2 days ago
Deduplicator
11.9k1950
asked 2 days ago
prog511prog511
61
edited 2 days ago
Deduplicator
11.9k1950
edited 2 days ago
Deduplicator
11.9k1950
edited 2 days ago
Deduplicator
11.9k1950
11.9k1950
asked 2 days ago
prog511prog511
61
asked 2 days ago
prog511prog511
61
asked 2 days ago
prog511prog511
61
61
$begingroup$
Is there a reason to not useopendir/readdirAPI?
$endgroup$
– vnp
yesterday
$begingroup$
This is much faster for dirs with too many files .
$endgroup$
– prog511
yesterday
add a comment |
$begingroup$
Is there a reason to not useopendir/readdirAPI?
$endgroup$
– vnp
yesterday
$begingroup$
This is much faster for dirs with too many files .
$endgroup$
– prog511
yesterday
$begingroup$
Is there a reason to not use
opendir/readdir API?$endgroup$
– vnp
yesterday
$begingroup$
Is there a reason to not use
opendir/readdir API?$endgroup$
– vnp
yesterday
$begingroup$
This is much faster for dirs with too many files .
$endgroup$
– prog511
yesterday
$begingroup$
This is much faster for dirs with too many files .
$endgroup$
– prog511
yesterday
add a comment |
0
active
oldest
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$begingroup$
Is there a reason to not use
opendir/readdirAPI?$endgroup$
– vnp
yesterday
$begingroup$
This is much faster for dirs with too many files .
$endgroup$
– prog511
yesterday